A degradable zinc-based composite material for biomedical stents and a preparation method thereof

Abstract

The present application relates to the technical field of composite materials, and particularly relates to a degradable zinc-based composite material for biomedical stents and a preparation method thereof, which comprises the following steps: taking zinc sheets after surface cleaning, coating hydroxyapatite on the surface of the zinc sheets after surface cleaning, stacking the zinc sheets coated with hydroxyapatite and the zinc sheets without hydroxyapatite coating, and rolling the zinc sheets with hydroxyapatite inside the stack; folding the zinc sheets after each rolling pass, and then continuing to roll; repeating the folding-rolling until the desired rolling pass; and after the obtained sample is pressed into a block, performing multi-pass hot rolling, thereby obtaining the degradable zinc-based composite material for biomedical stents. The present application adopts a cumulative roll bonding preparation process, which can effectively improve the combination of hydroxyapatite and zinc, and improve the dispersity of hydroxyapatite in zinc, and can effectively refine the grains and strengthen the matrix, so as to finally obtain a zinc / hydroxyapatite composite material with uniform structure and excellent performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite materials, in particular to a degradable zinc-based composite material for biomedical stents and a preparation method thereof. BACKGROUND

[0002] At present, the biomedical degradable implant metal materials for bone fixation mainly include three alloy systems: magnesium-based, zinc-based and iron-based materials. A large number of research results show that the standard electrode potential of the base metal is inversely proportional to the degradation rate, the lower the standard electrode potential of the metal, the faster the corrosion rate. The standard electrode potential of magnesium is-2.372V, and the standard electrode potential of iron is-0.447V, so the degradation rate of magnesium-based alloy or composite material is too fast to maintain mechanical function for a long time; the degradation rate of iron-based alloy is relatively slow, and the degradation product can also play a protective role on the substrate and support the tissue, thereby reducing the degradation rate of the iron-based alloy medical implant, but it will seriously hinder the recovery process of the tissue itself. The standard electrode potential of zinc is-0.763V, which is between magnesium and iron, so its degradation rate is relatively moderate, and the zinc ions generated during degradation are one of the essential elements of the human body, which makes the zinc-based alloy or composite material medical implant can degrade at an appropriate rate in the body, matching the normal recovery and development of human tissue and organs, and can fully play the characteristics and functions of the medical degradable alloy. However, the disadvantage of zinc is that the mechanical strength required for implant application is poor, which restricts its use in the human body.

[0003] The advantages of hydroxyapatite over graphene, carbon nanotubes and other reinforcing phases are (1) it is the main inorganic component of human bone tissue, which can be artificially synthesized and applied to human bone tissue repair. (2) The calcium and phosphorus in the body will be released from the surface of the material, and the body will grow new tissue after absorbing these substances. However, hydroxyapatite also has the following disadvantages: (1) poor mechanical properties, which makes it impossible to use it alone to make biological devices (2) when combined with other materials, it will also cause agglomeration, which will change the structure of the material and affect the mechanical properties. SUMMARY

[0004] One of the purposes of the present application is to provide a preparation method of a degradable zinc-based composite material for biomedical stents, which can effectively improve the combination of hydroxyapatite and zinc by using the cumulative roll forming process, and improve the dispersion of hydroxyapatite in zinc, while effectively refining the grain and strengthening the matrix, and finally obtaining a zinc / hydroxyapatite composite material with uniform structure and excellent performance.

[0005] The second object of the present application is to provide a degradable zinc-based composite material for biomedical stents, which has good dispersibility, low defect density, and high strength and toughness while achieving good degradability and biocompatibility.

[0006] The scheme adopted for achieving one of the objects of the present application is a preparation method of a degradable zinc-based composite material for biomedical stents, comprising the following steps:

[0007] (1) Take the surface-cleaned zinc sheet, coat hydroxyapatite on the surface of the surface-cleaned zinc sheet, and stack the zinc sheet coated with hydroxyapatite and the zinc sheet without hydroxyapatite coating, with the hydroxyapatite located inside the stack, and then roll it; fold the zinc sheet after each pass of rolling, and then continue rolling; repeat the folding-rolling until the desired number of passes.

[0008] (2) After the sample obtained in step (1) is pressed into a block, it is subjected to multi-pass hot rolling, and the degradable zinc-based composite material for biomedical stents is obtained.

[0009] Preferably, in step (1), the cleaning process includes removing the oxides on the surface of the zinc sheet by shot blasting.

[0010] Preferably, in step (1), the deformation amount of the sample in the thickness direction is controlled to be 50% to 70% for each pass of rolling, and the cumulative rolling is 30 to 40 passes.

[0011] Preferably, in step (1), the zinc sheet is at least two pieces, when the zinc sheet is more than two pieces, the hydroxyapatite layer is at least one layer, and when the hydroxyapatite layer is multiple layers, the hydroxyapatite layers are uniformly distributed in the stack.

[0012] Preferably, in step (2), the pressure for pressing into a block is 30 to 40 kN.

[0013] Preferably, in step (2), the hot rolling temperature is 200 to 300℃.

[0014] Preferably, in step (2), the hot rolling pass is 6 to 8 passes, and the final cumulative deformation amount in the thickness direction is 50% to 80%.

[0015] Preferably, in step (2), the mass percentage of hydroxyapatite in the composite material is greater than 0 and less than or equal to 20%.

[0016] Preferably, in step (2), the grain size of the zinc matrix in the composite material is 400 to 500 nm.

[0017] The scheme adopted for achieving the second object of the present application is a degradable zinc-based composite material for biomedical stents, which is prepared by the above-mentioned preparation method.

[0018] The principle of the present application is mainly that: through multi-pass rolling deformation at room temperature, due to the increase of the cumulative deformation caused by the rolling pass, the zinc matrix will undergo plastic strain, and the nano-hydroxyapatite particles will move with the plastic strain of the zinc matrix. When enough rolling passes are reached, a uniform dispersion effect in the zinc matrix can be obtained. And through pressing, the density of the sample can be further improved. Finally, through high-temperature rolling, the combination of the zinc matrix and the hydroxyapatite particles in the sample can be made more closely, so as to obtain a composite material with excellent performance. At the same time, the finer the hydroxyapatite particles, the higher the activity, and the nano-hydroxyapatite is undoubtedly a good material for making biomedical devices, and its biocompatibility and tissue compatibility are not a problem.

[0019] The present application has the following advantages and beneficial effects:

[0020] 1. The preparation method of the present application adopts a cumulative roll bonding process, which can be carried out in a room temperature environment, can effectively improve the combination of hydroxyapatite and zinc, and improve the dispersion of hydroxyapatite in zinc, and can effectively refine the grain size and strengthen the matrix, and finally obtain a zinc / hydroxyapatite composite material with uniform structure and excellent performance.

[0021] 2. The preparation method of the present application can adjust the corrosion performance and biocompatibility of the composite material by changing the content and distribution of hydroxyapatite, and optimize the interaction between the metal matrix composite material and the surrounding human tissues.

[0022] 3. The preparation method of the present application only uses industrial rolling mill, hydraulic press and salt bath pot, which is simple in equipment and low in cost, and is suitable for industrial production.

[0023] 4. The preparation method of the present application can obtain a composite material with high mass fraction, extremely high hardness, and good degradability, biocompatibility and thermal stability.

[0024] 5. The zinc-based composite material prepared by the preparation method of the present application has a hardness improvement rate of up to 3 times, a tensile strength improvement rate of up to 1.7 times, and a corrosion current density improvement rate of up to 2.2 times compared with pure zinc matrix, so the composite material has good strength, degradability and biocompatibility. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 (a) is a light microscope photo of the 1wt% hydroxyapatite particle reinforced zinc-based composite material finally obtained in Example 1 of the present application. Figure 1 (b) is a high-magnification scanning electron microscope image, and the grain size is about 400-500nm;

[0026] Figure 2(a) is the optical micrograph of the 3wt% hydroxyapatite particle reinforced zinc matrix composite material finally obtained in Example 2 of the present application. Figure 2 (b) is its high-magnification scanning electron micrograph, and the grain size is about 400-500 nm;

[0027] Figure 3 is the optical micrograph of the 5wt% hydroxyapatite particle reinforced zinc matrix composite material finally obtained in Example 3 of the present application.

[0028] Figure 4 is the optical micrograph of the 10wt% hydroxyapatite particle reinforced zinc matrix composite material finally obtained in Example 4 of the present application.

[0029] Figure 5 is the optical micrograph of the 20wt% hydroxyapatite particle reinforced zinc matrix composite material finally obtained in Example 5 of the present application. DETAILED DESCRIPTION

[0030] In order to better understand the present application, the following examples are further illustrations of the present application, but the content of the present application is not limited to the following examples.

[0031] Example 1

[0032] (1) Cut 75x50x0.3mm pure zinc sheets, take 4 pieces as the original matrix, and perform shot blasting treatment on the surface of the sample. According to the 1wt% hydroxyapatite in the composite material, weigh the corresponding hydroxyapatite, pour an appropriate amount of alcohol into the beaker after weighing the powder, and use an ultrasonic cleaning instrument to oscillate for 5min to uniformly mix it in the alcohol to form a nanoparticle suspension. Until no obvious particle precipitation is found during stirring. The hydroxyapatite-ethanol suspension is uniformly coated on the surface of three of the pure zinc sheets, a heater is placed next to the zinc sheet to accelerate the evaporation of ethanol, and after evaporation, the three zinc sheets coated with hydroxyapatite are stacked, and the zinc sheet without hydroxyapatite is stacked on the outermost layer, so that the outermost surface is the surface without hydroxyapatite, and the laminated material is obtained.

[0033] (2) Put the laminated material into a steel plate and roll it at room temperature in multiple passes, with each pass divided into two steps of rolling, and the down pressure is controlled at 30%-70%. After each pass of rolling, the material is folded in half, and then the next pass of rolling is performed. Repeat the above process until the total rolling passes are 30 passes.

[0034] (3) Cut an aluminum ring with a diameter of 10mm and a height of 10mm, first pad a layer of titanium foil on the lower surface, uniformly fill the sample obtained in the previous step into the aluminum ring, which is generally the same height as the aluminum ring, and then cover the upper surface with a piece of titanium foil. Use a hydraulic press to press the sample into a sheet-shaped material with a thickness of about 3mm.

[0035] (4) Put the sheet material pressed by the hydraulic press into a salt bath pot, and keep it at 200°C for 3 minutes. Immediately after the holding time, take the sample out of the salt bath pot and roll it. Repeat the process of holding, rolling and polishing for 6 passes, and the deformation amount of each pass is selected as 10%. Finally, a degradable zinc / hydroxyapatite composite material for biomedical stents is obtained.

[0036] Figure 1 (a) is the optical microscope image of the composite material finally prepared in this example. It can be seen from the image that there is no obvious defect in the obtained composite material, and the nano-hydroxyapatite particles are uniformly dispersed in the zinc matrix. Figure 1 (b) is the SEM image of the composite material prepared in this example. It can be seen from the image that the grain size of the zinc matrix is 400-500 nm, which is ultra-fine grain. The zinc-based composite material with uniformly dispersed hydroxyapatite particles obtained in this example has a hardness value of 46.6 Hv, which is 1.2 times higher than that of pure zinc matrix.

[0037] Example 2

[0038] (1) Cut 75x50x0.3mm pure zinc sheets, take 4 as the original matrix, and perform shot blasting treatment on the surface of the sample. According to the 3wt% hydroxyapatite in the composite material, weigh the corresponding hydroxyapatite, pour an appropriate amount of alcohol into the beaker after weighing the powder, and use an ultrasonic cleaning instrument to oscillate for 5min to uniformly mix it in the alcohol to form a nano-particle suspension. Until no obvious particle sedimentation is found during stirring. The hydroxyapatite-ethanol suspension is uniformly coated on the surface of three of the pure zinc sheets, and a heater is placed next to the zinc sheet to accelerate the evaporation of ethanol. After evaporation, the three zinc sheets coated with hydroxyapatite are stacked, and the zinc sheet without hydroxyapatite is stacked on the outermost layer, so that the outermost surface is the surface without hydroxyapatite, and the laminated material is obtained.

[0039] (2) Put the laminated material into a steel plate and roll it at room temperature in multiple times, with each pass being divided into two steps of rolling, and the down pressure is controlled at 30%-70%. After each pass of rolling, the material is folded in half, and then the next pass of rolling is performed. Repeat the above process until the total rolling passes are 30.

[0040] (3) Cut an aluminum ring with a diameter of 10mm and a height of 10mm, and first pad a layer of titanium foil on the lower surface. Fill the sample obtained by cold rolling in the previous step into the aluminum ring, which is generally the same height as the aluminum ring, and then cover the upper surface with a piece of titanium foil. Use a hydraulic press to press the sample into a sheet material with a thickness of about 3mm.

[0041] (4) Put the sample after pressing by hydraulic press into the salt bath pot, and keep it at 200°C for 24 minutes. Immediately after the holding time, take the sample out of the salt bath pot and roll it. Repeat the process of holding, rolling and polishing for 6 passes, and the deformation of each pass is selected as 10%. Finally, the degradable zinc / hydroxyapatite composite material for biomedical stent is obtained.

[0042] Figure 2 (a) The optical microscope image of the composite material finally prepared in this example shows that there is no obvious defect in the sample, and the nano-hydroxyapatite particles are uniformly dispersed in the zinc matrix. Figure 2 (b) The scanning electron microscope image of the composite material prepared in this example shows that the grain size of the zinc matrix is 400-500 nm, which is ultra-fine grain. The hardness value of the final composite material is 90.2 Hv, which is 2.4 times higher than that of the matrix. Its tensile strength is 138.1 MPa, which is 1.4 times that of the matrix, the elongation at break is 12.8%, and the corrosion current density is 10 -5 A / cm 2 , which is 2 times that of the matrix, and has good degradability.

[0043] Example 3

[0044] (1) Cut 75x50x0.3mm pure zinc sheet, take 4 pieces as the original matrix, and perform shot blasting treatment on the surface of the sample. According to the 5wt% hydroxyapatite in the composite material, weigh the corresponding hydroxyapatite, pour an appropriate amount of alcohol into the beaker after weighing the powder, and use an ultrasonic cleaning instrument to oscillate for 5 minutes to uniformly mix it in the alcohol to form a nano-particle suspension. Until no obvious particle precipitation is found during stirring. The hydroxyapatite-ethanol suspension is uniformly coated on the surface of three of the pure zinc sheets, and a heater is placed next to the zinc sheet to accelerate the evaporation of ethanol. After evaporation, the three zinc sheets coated with hydroxyapatite are stacked, and the zinc sheet without hydroxyapatite is stacked on the outermost layer, so that the outermost surface is the surface without hydroxyapatite, and the layered material is obtained.

[0045] (2) Put the layered material into the steel plate and roll it at room temperature in multiple passes, with each pass divided into two steps of rolling, and the down pressure controlled at 30%-70%. After each pass of rolling, fold the material and then proceed to the next pass of rolling. Repeat the above process until the total rolling passes are 35 passes.

[0046] (3) Cut an aluminum ring with a diameter of 10 mm and a height of 10 mm, and first pad a layer of titanium foil on the lower surface. Fill the sample obtained in the previous step into the aluminum ring, which is generally the same height as the aluminum ring, and then cover the upper surface with a piece of titanium foil. Use a hydraulic press to press the sample into a sheet-shaped material with a thickness of about 3 mm.

[0047] (4) Put the sample after pressing by hydraulic press into the salt bath pot, and keep it at 250°C for 3 minutes. Immediately after the holding time, take the sample out of the salt bath pot and roll it. Repeat the process of holding, rolling and polishing for 7 passes, and the deformation of each pass is selected as 10%. Finally, the degradable zinc / hydroxyapatite composite material for biomedical stent is obtained.

[0048] Figure 3 The optical microscope image of the composite material finally prepared in this example is shown in the figure. It can be seen from the figure that there is no obvious defect in the sample, and the nano-hydroxyapatite particles are uniformly dispersed in the zinc matrix. The hardness value of the zinc-based composite material prepared in this example is 94.6 Hv, which is 2.5 times higher than that of the matrix. The tensile strength is 170.5 MPa, which is 1.7 times higher than that of the matrix, the ductility is 2%, and the corrosion current density is 1.1x10 -5 A / cm 2 , which is 2.2 times that of the matrix, and has good degradability.

[0049] Example 4

[0050] (1) Cut 75x50x0.3mm pure zinc sheet, take 4 pieces as the original matrix, and perform shot blasting treatment on the surface of the sample. According to the 10wt% hydroxyapatite in the composite material, weigh the corresponding hydroxyapatite, pour an appropriate amount of alcohol into the beaker after weighing the powder, and use an ultrasonic cleaning instrument to oscillate for 5min to uniformly mix it in the alcohol to form a nano-particle suspension. Until no obvious particle sedimentation is found during stirring. The hydroxyapatite-ethanol suspension is uniformly coated on the surface of three of the pure zinc sheets, and a heater is placed next to the zinc sheet to accelerate the evaporation of ethanol. After evaporation, the three zinc sheets coated with hydroxyapatite are stacked, and the zinc sheet without hydroxyapatite is stacked on the outermost layer, so that the outermost surface is the surface without hydroxyapatite, and the laminated material is obtained.

[0051] (2) Put the laminated material into the steel plate and roll it at room temperature in multiple passes, with each pass divided into two steps of rolling, and the pressing amount controlled at 30%-70%. After each pass of rolling, the material is folded in half, and then the next pass of rolling is performed. Repeat the above process until the total rolling passes are 40 passes.

[0052] (3) Cut an aluminum ring with a diameter of 10mm and a height of 10mm, and first pad a layer of titanium foil on the lower surface. Fill the sample obtained in the previous step into the aluminum ring, which is generally the same height as the aluminum ring, and then cover the upper surface with a piece of titanium foil. Use a hydraulic press to roll the sample into a sheet-shaped material with a thickness of about 3mm.

[0053] (4) The sample after hydraulic press is put into a salt bath pot and kept at 300°C for 3 minutes. After the time is up, the sample is immediately taken out of the salt bath pot and rolled. The process of keeping, rolling and polishing is repeated for 8 passes, and the deformation of each pass is selected as 10%. Finally, the degradable zinc / hydroxyapatite composite material for biomedical stents is obtained.

[0054] Figure 4 The optical microscope image of the composite material finally prepared in this embodiment is shown in the figure. It can be seen from the figure that there is no obvious defect in the sample, and the nano-hydroxyapatite particles are uniformly dispersed in the zinc matrix. The zinc-based composite material with uniformly dispersed hydroxyapatite particles finally obtained in this embodiment has a hardness value of 110 Hv, which is 2.9 times higher than that of the matrix.

[0055] Example 5

[0056] (1) Cut 75x50x0.3mm pure zinc sheets, take 4 as the original matrix, and perform shot blasting treatment on the surface of the sample. According to the 20wt% hydroxyapatite in the composite material, the corresponding hydroxyapatite mass is weighed, and a proper amount of alcohol is poured into the beaker after weighing the powder. The ultrasonic cleaning instrument is vibrated for 5 minutes to uniformly mix it in the alcohol to form a nano-particle suspension. Until no obvious particle precipitation is found during stirring. The hydroxyapatite-ethanol suspension is uniformly coated on the surface of three of the pure zinc sheets, and a heater is placed next to the zinc sheets to accelerate the evaporation of ethanol. After evaporation, the three zinc sheets coated with hydroxyapatite are stacked, and the zinc sheet without hydroxyapatite is stacked on the outermost layer, so that the outermost surface is the surface without hydroxyapatite, and the laminated material is obtained.

[0057] (2) Put the laminated material into a steel plate and roll it at room temperature in multiple passes, with each pass divided into two steps of rolling, and the down pressure controlled at 30%-70%. After each pass of rolling, the material is folded in half, and then the next pass of rolling is performed. Repeat the above process until the total rolling passes are 40.

[0058] (3) Cut an aluminum ring with a diameter of 10mm and a height of 10mm, and first place a layer of titanium foil on the lower surface. The sample obtained by cold rolling in the previous step is uniformly filled into the aluminum ring, which is generally the same height as the aluminum ring. Then cover the upper surface with a piece of titanium foil, and use a hydraulic press to roll the sample into a sheet-shaped material with a thickness of about 3mm.

[0059] (4) The sample after hydraulic press is put into a salt bath pot and kept at 300°C for 3 minutes. After the time is up, the sample is immediately taken out of the salt bath pot and rolled. The process of keeping, rolling and polishing is repeated for 8 passes, and the deformation of each pass is selected as 10%. Finally, the degradable zinc / hydroxyapatite composite material for biomedical stents is obtained.

[0060] Figure 5 The optical micrograph of the composite material prepared in this example is shown in the figure. It can be seen from the figure that there is no obvious defect in the sample, and the nano-hydroxyapatite particles are uniformly dispersed in the zinc matrix. The zinc-based composite material with uniformly dispersed hydroxyapatite particles obtained in this example has a hardness value of 114 Hv, which is 3 times higher than that of the matrix.

[0061] The above describes the preferred embodiments of the present application, of course, cannot be limited to the scope of the present application, should be noted that, for those skilled in the art, without departing from the principles of the present application, can also make a number of improvements and changes, these improvements and changes are also considered to be within the scope of the present application.

Claims

1. A method for preparing a degradable zinc-based composite material for biomedical stents, characterized in that, The method comprises the following steps: (1) taking the surface-cleaned zinc sheet, coating hydroxyapatite on the surface of the surface-cleaned zinc sheet, stacking the zinc sheet coated with hydroxyapatite and the zinc sheet not coated with hydroxyapatite, and rolling the zinc sheet with hydroxyapatite inside the stack; folding the zinc sheet after each rolling pass, and then continuing to roll; repeating the folding-rolling until the desired rolling pass is reached; (2) after the sample obtained in step (1) is pressed into a block, it is subjected to multi-pass hot rolling, thereby obtaining the biodegradable zinc-based composite material for biomedical stents; in step (1), the cleaning process comprises removing the oxide on the surface of the zinc sheet by shot blasting; in step (1), the deformation amount of the sample in the thickness direction is controlled to be 50% to 70% in each rolling pass, and the cumulative rolling is 30 to 40 passes; in step (2), the pressure for pressing into a block is 30 to 40 kN; in step (2), the hot rolling temperature is 200 to 300℃; in step (2), the hot rolling pass is 6 to 8 passes, and the final cumulative deformation amount in the thickness direction is 50% to 80%; in step (2), the grain size of the zinc matrix in the composite material is 400 to 500 nm.

2. The method for preparing a degradable zinc-based composite material for a biomedical stent according to claim 1, characterized in that: in step (1), the zinc sheet is at least two pieces, when the zinc sheet is more than two pieces, the hydroxyapatite layer is at least one layer, and when the hydroxyapatite layer is multiple layers, the hydroxyapatite layers are uniformly distributed in the stack.

3. The method for preparing the degradable zinc-based composite material for a biomedical stent according to claim 1, characterized in that: in step (2), the mass percentage of hydroxyapatite in the composite material is greater than 0 and less than or equal to 20%.

4. A degradable zinc-based composite material for biomedical stents, characterized by: The preparation method is prepared by any one of claims 1-3.

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